1. Field of the Invention
The present invention relates to four stroke internal combustion engines and exhaust gas scavenging. More specifically, the present invention pertains to an improved exhaust port venting system in which exhaust valve guides are fitted with a compressed air functionality that forces air into the combustion chamber, accelerating the outflow of exhaust gases and promoting their exit through the exhaust manifold.
An internal combustion engine is akin to an air pump, in which air is pumped into a combustion chamber, compressed with atomized fuel by a piston-cylinder device, ignited and then exhausted from the chamber. The intake and exhaust of gases is accomplished by a series of valves that open and close at predetermined times in the piston cycle. Four stroke combustion engines, in particular, are internal combustion engines that comprise one power stroke for every four strokes of the piston. The four strokes of these engines are the intake stroke, the compression stroke, the combustion stroke, and finally the exhaust stroke. Air and fuel are brought into the cylinder during the intake stroke, compressed and ignited during the compression stroke, burned and expanded during the combustion stroke, and then combustion byproducts are exited from the cylinder during the exhaust stroke.
The volumetric efficiency of an internal combustion engine is measured as the ratio of fuel and air that actually enters a combustion cylinder during intake to the capacity thereof under static conditions. Volumetric efficiency measures the efficiency with which air can be move through an engine, with higher values leading to more powerful and more efficient engines. Higher amounts and uninterrupted passage of air through the engine provides for higher quantities of fuel that can be added, and in turn produce a higher power output. Volumetric efficiency can be improved through several means, including larger valves or an increased quantity of valves for improved passage of air and fuel, application of secondary induction systems like turbochargers and superchargers which force air into the cylinders, or improved intake manifolds that streamline the ports of an engine for smoother air flow. Still other systems focus solely on clearing exhaust gases from the combustion chamber and exhaust manifold after combustion to reduce back pressure or stalling of air within the exhaust manifold.
The process of drawing in fresh air into and removing exhaust gases from a combustion chamber is known as scavenging. During the exhaust stroke, the piston reduces the volume in the cylinder as it advances from bottom dead center (BOC) to top dead center (TOC). As the volume within the cylinder reduces, its contents become compressed, manifesting in a pressure on the exhaust gas that forces it from the cylinder through an open exhaust valve. Engine timing systems control the opening and closing of the valves as the cylinder advances through its four strokes. The path from intake to exhaust must be kept in sync to utilize the full potential of the engine's power and efficiency.
It is sometimes common for an engine to insufficiently clear the exhaust gases from a cylinder during the exhaust stroke. Conventional engine timing systems may not operate with 100% efficiency, especially during times of high backpressure in the exhaust system, which retards the air flow out of the engine prior to the beginning of the next intake stroke. A common method of treating this deficiency includes reducing the head loss or drag within the exhaust system, including making its path a more free-flow design. Removing emission systems and muffling means from the exhaust system have been used in closed-course racing, however these solutions are not suitable for commercial use, where everyday driving introduces considerable emissions into the atmosphere and the noise generated from an unmuffled engine is not appropriate in most settings.
Still other methods are directed at increasing the flow of exhaust gases from the cylinder, the exhaust manifold or the exhaust system. The present invention is an engine component that is specifically designed to compensate for a deficiency in removing exhaust gases from a cylinder and exhaust manifold, without the drawbacks related to removing exhaust and emissions components. The present invention is designed to be installed within any four-stroke internal combustion engine, and functions by forcibly removing exhaust gases from an engine cylinder during the exhaust stroke. The device utilizes a modified valve guide that delivers compressed air into the combustion chamber directly under the exhaust valve. The exhaust is thoroughly vented from the system by the introduction of pressurized air, as the compressed air forces the exhaust gas through the exhaust port and through the exhaust manifold prior to the exhaust valve reclosing.
2. Description of the Prior Art
Several devices have been disclosed in the art that attempt to forcibly remove exhaust gases from an engine via compressed air or similar means. U.S. Pat. No. 6,167,700 to Lampert is one such device, in which a ram air port is disclosed for capturing outside air through an intake, compressing it through a nozzle, and combining it with exhaust gases exiting a cylinder via a plenum chamber. This device discloses a system that is utilized downstream of the engine exhaust ports, along the exhaust pipes prior to entering the catalytic converter and muffler. While it may be useful for efficiently moving air through an exhaust pipe, its structure and intent is sufficiently different from the present invention. The forced air is captured from ambient air rushing passed the moving vehicle, as opposed to a system utilizing on-demand compressed air to force out exhaust gases from an engine cylinder.
U.S. Pat. No. 3,522,702 to Grosseau is a system more closely related to the present invention, wherein an air pump and associated pipeline is provided to inject air into the exhaust manifold of an engine to purify exhaust gases as they exit the engine. The system promotes efficient conversion of carbon monoxide (CO) in to carbon dioxide (CO2) as the exhaust gases leave the manifold and enter the catalytic converter. While this system utilizes compressed air, its placement is within the exhaust manifold, and its structure significantly diverges from the present invention, wherein an exhaust valve guide is utilized to introduce compressed air. The present invention allows efficient airflow through the cylinder as the piston reaches top dead center and when the exhaust port is open. This aids in the pressurization and circulation of the exhaust gases, and allows efficient evacuation thereof through an open exhaust port or ports.
U.S. Pat. No. 3,948,229 to Abthoff describes a specifically designed intake and suction manifold for controlling the air flow through a v-shaped cylinder block engine. Similar to the Grosseau patent, the Abthoff patent relies on a forced air supply that forces air into the exhaust manifold for aiding escaping exhaust gases, rather than one that introduces the compressed air from a valve seat into the engine cylinder.
U.S. Pat. No. 3,116,596 to Boehme is another exhaust flow devices that describes a specifically designed flywheel that supplies air induction into an exhaust system downstream from an engine block. While this air induction system is useful for improving airflow through an exhaust system and preventing back pressure, the structure of the device and its installation are considerably different from the present invention. The air induction is supplied farther downstream than the engine exhaust valves, which are situated adjacent to the engine cylinders within the engine block.
The devices disclosed in the prior art involve improving air flow through an exhaust system, starting from the exhaust manifold through the exhaust system. The primary function of these devices and the field of the invention pertain to efficient flow of air through an engine, and efficient evacuation of exhaust gases. These devices may improve downstream flow in an exhaust and aid in relieving backpressure on the system; however they are not suited for thoroughly discharging exhaust gases directly from an engine cylinder for evacuation into the exhaust manifold. They rely on devices that improve air circulation, suction or pressure to draw gases away from an exhaust manifold, while the present invention is seated directly below the exhaust valves and delivers compressed air during the exhaust stroke to drastically improve evacuation of gases. This provides a clean combustion chamber prior to the initiation of the intake stroke, wherein a fresh charge of air and fuel are brought back into the cylinder prior to combustion. By removing unburned fuel and combustion byproducts from the cylinder, the engine can operate more efficiently. The improved flow from intake to exhaust also increases the amount of air that can be introduced in the intake charge, resulting in higher amounts of fuel and added power. Overall, the volumetric efficiency of the system is considerably improved, as air is efficiently removed from the engine cylinders during an exhaust stroke prior to intake of a fresh charge.
In this way, the present invention substantially diverges in design elements from the prior art. Consequently it is clear that that present invention is not described by the art and that a need exists for an improved forced air exhaust system that provides efficient evacuation of exhaust gases via compressed air delivered through a modified valve guide device. In this regard the instant invention substantially fulfills these needs.